18CrMo4 Structural Steel Bar

 

18CrMo4 (1.7243 ) is a kind of steel with high permanent strength at 500~550℃. When the temperature exceeds 550℃, the oxidation resistance becomes worse and the creep strength is significantly reduced. 18CrMo4 belongs to the European standard alloy carburized steel, belongs to standard: EN 10084-2008. 18CrMo4 (1.7243) alloy structural steel has good process performance and welding performance, and has a higher endurance strength at 500-550°C. 

 

When the temperature exceeds 550°C, the oxidation resistance will deteriorate and the creep strength will decrease significantly. If under 500-550 ℃ for a long time, the thermal strength of 18CrMo4 steel will decrease, and the strength will decrease. 18CrMo4 is used to make 510℃ high and medium pressure steam pipes, headers, superheaters and forgings whose tube wall temperature is 550℃.

 

18CrMo4 structural steel bar in stock

 

 

Chemical Composition:

 
C(%)Si(%)Mn(%)P(%)S(%)Cr(%)Ni(%)Cu(%)Mo(%)
0.15~0.21≤0.400.60 ~ 0.90≤0.035≤0.0350.90~1.20≤0.030≤0.0300.15 ~ 0.25

 

Mechanical properties - 18CrMo4:

 

Mechanical and physical properties
Tensile strengthRm> 1080 MPa
Yield pointRe> 880 MPa
ContractionZ> 50%
ElongationA> 10%
Notch toughnessKU2> 72 J
Hardness in softened stateHB< 217 HB
Densityρ7,85 kg/dm3

 

Mechanical properties for individual dimensions:

 

 

Mechanical properties after hardening
PropertiesDimensions
11mm30mm63mm
Tensile strengthRm920 - 1270 MPa820 - 1170 MPa710 - 1060 MPa
Yield pointRe> 600 MPa> 540 MPa> 480 MPa
Notch toughnessKU> 25 J> 25 J> 25 J
ElongationA> 9 %> 10 %> 11 %

 

 

Heat treatment of 18CrMo4 steel:

 

 

ProcessCoolingTemperatures
Normalizing annealing

in air

870 - 900℃

Softening annealing

650 - 700℃
Carburizing in powder
  • in oil or water
  • 160 - 250℃ in hot baths
  • 580 - 680 °C in salt baths
  • in carburizing box
880 - 950℃
Carburization in salt baths900 - 950℃
Gas carburization880 - 900℃
Hardening (I)
  • in oil or water
  • 180 - 300℃ in hot baths
860 - 900℃
Hardening (II)
  • in oil or water
  • 160 - 250℃ in hot baths
800 - 840℃

Tempering

170 - 200℃

 

     

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